The present invention relates to a method for vibration damping of driven elements of workpiece transport devices in and on shaping machines, particularly presses and punches.
The mechanical parts of electrically driven elements of workpiece transport devices in and on shaping machines, especially presses and punches, must be as rigid and vibration-damping as possible because of the acceleration forces that develop, the weight of the elements, the vibrational excitations caused by the drives of the elements, and the vibration of the press.
Because of these requirements, the mechanical elements are usually cumbersome and expensive. For example, in order to keep the masses to be moved low, fiber-bonded materials are used to achieve the desired stiffness of the mechanical elements.
To achieve this goal, mechanical damping devices are known in practice. Thus, for example, DE-PS 30 04 862 discloses a transfer device for transporting workpieces from station to station on a press, which has a braking device that counteracts the rotational movement of a shaft.
German Patent 22 00 754 discloses a drive for gripper rail lengthwise movement on mechanical presses, especially transfer presses, in which the individual masses of the components to be moved as well as the distances to be traveled are kept as low as possible. Thus, even when it is used on presses with a high number of strokes, for example high-speed transfer presses, quiet, low-vibration operation with low wear of the transmission elements is sought to be achieved.
However, a disadvantage of the above-mentioned approaches for achieving the goal is that the devices are complex and hence expensive to manufacture and install.
The present invention therefore has as its object a method for vibration damping of driven elements of workpiece transport devices in and on shaping machines, which is both economical and simple.
According to the present invention, this has been achieved by providing that the vibration damping is performed actively, with a measured state value of the driven component or one reconstructed by means of an observer is determined, with the state value being entered into a damping regulator, which regulator acts on drive of the driven elements, with a damping regulating circuit being provided in addition to a position regulating circuit.
By providing active vibration damping that is implemented by a damping regulating circuit in addition to a position regulating circuit, complex mechanical devices can be completely eliminated since the vibration damping is accomplished by directly influencing the drive of the driven components.
To determine the movement of the center of the transfer rails that can occur, for example, during vibration, a state value or characterizing value of the driven element is determined directly or indirectly. This value is fed into the damping regulator and used as a measured value for the damping regulation and is evaluated by the latter.